Method of making fastener units



July 28, 1936. E, RENTICE 2,048,709

METHOD OF MAKING FASTENER UNITS Filed March 31, 1934 fiwerlzar 660796 lfprenil'e'e Patented July 28, 193

UNITED STATES- PATENT OFFICE This invention pertains to separable fasteners of the kind in which opposed series of fastener units, mounted upon flexible stringers or equivalent supports, are moved into and out of engagement by a slider, and relates more particularly to an improved fastener unit and to a method of making such a unit.

In my Patent No. 1,658,392, dated February '7, 1928, I disclosed a type of fastener unit having certain features which have been proven valuable in a wide commercial use. As disclosed in the patent drawing, the outer or free ends of the units (that is to say, the ends which project outwardly beyond the stringer when the units are mounted on the latter) are rounded or arcuate in vertical section. These rounded outer ends permit the units of one series to gnter between those of the other series much more easily and smoothly than when the outer ends of the units are cut off square, as in the usual practice, and thus when the units have such rounded outer ends the slider moves very easily and quietly, and with a minimum of friction. Moreover, there is no danger of damage to the user or to objects with which the fastener may come into contact such as might result from the presence of sharp edges or corners of the exposed ends of the units.

However, since it has been common, in making these fasteners on a commercial scale, to punch or stamp the units from sheet-like metal and immediately set them onto the stringers, and

although the desirability of rounded ends, as shown in said patentdrawing has been well understood, it has not heretofore been considered practical to provide the units with such rounded ends, as involving too great a departure from the customary mode of making and applying them. Thus the outer ends of the units are ordinarily left angular (unrounded) just as delivered from the dies. These rough, unfinishedends, which are sometimes burred if the dies are dull, cause a diflicult, harsh, and noisy action of the slider, although when engaged, they have all of the holding power that may be desired.

Inorder to overcome this defect, without resort to a secondary or finishing operation, I have devised the present and improved method of procedure which does not in the least interfere with the usual commercial method of forming and attaching the units to the stringers. This novel method not only produces units of the desired shape having nicely finished outer ends, but at the same time results in a very substantial sav ing in the amount of raw material required in producing the units. In accordance with a preferred method, not only does the unit have the des1red rounded outer end, but at this outer end. where the wear of contact with opposed units is greatest, the unit is furnished with a dense and hard outer surface well adapted to withstand a friction and wear for a long period.

In the accompanying drawing, wherein I have illustrated my improved unit and certain desirable steps in-its production,

Fig. 1 is a fragmentary front elevation. to 10 large scale, illustrating a fastener comprising units having smoothly rounded outer ends substantially such as result from the practice of my invention;

Fig. 2 is a transverse section, to larger scale, 15 through a strip of flat wire (constituting a desirable form of raw material) from which my units are made in accordance with the improved method;

Fig. 3 is a plan view of a length of the flat 20 wire from which fastener units have been stamped or punched out in accordance with my invention;

Fig. 4 is a plan view of a completed fastener unit, to very large scale. as it appears before at- 25 tachment to the stringer;

Fig. 5 is a side elevation, partly in vertical section, of the unit of Fig. 4;

Fig. 6 is a bottom view of the unit of Fig. 4 attached to a stringer, the latter being shown in 30 section in broken lines;

Fig. 7 is a transversesection of a piece of flat stock such as is employed in making units in accordance with prior methods;

Fig. 8 is a plan view of a length of such stock 35 from which units have been cut by the usual method;

Fig. 9 is a plan view of a completed unit, to larger scale, made in accordance with the method illustrated in Fig. 8; and

Fig. 10 is a side elevation of the units of Fig. 9.

Referring to the drawing, the numerals l and 2 designate flexible stringers or other customary supports, preferably having beaded edges to which series of fastener units 3 and 4 respec- 45 tively are attached. At the upper ends of the series, the respective stringers are furnished with top end stops 5, and at the lower end of the fastener a stop 6 is provided. A slider I, which may conveniently be of the form described in my Patent No. 1,900,949, dated March 14, 1933, is employed for opening and closing the fastener.

In accordance with the present invention, I make my improved fastener units from a strip of sheet-like material, preferably from a flat wire 58 "8 produced by a drawing operation or by drawing and/or rolling. The result of such operations, as is well known, is to cause the fibrous structure of the material to extend in a generally longitudinal direction and to form a compact and dense outer layer or skin on the material. 7

Having provided such a wire, I feed this wire through a suitable mechanism, including dies of proper shape, designed to cut out and form the individual units one after another, successively, and, if desired, combined with means for attaching the units to the edge of a stringer as the units are successively formed. In feeding the wire through the cutting apparatus, I so dispose the parts that the openings I3 (Fig. 3) left, in the wire are nearer to one edge of the wire than to the other, and so that the outer ends l2 of the resulting fastener units are substantially unchanged portions of the original edge I2 of the wire. The end portion l2 of the fastener unit is thus smoothly rounded and comprises a hard, dense surface layer well calculated to resist wear.

The units as here illustrated are similar to those mentioned in my aforesaid Patent No. 1,658,392, having-the spaced legsor prongs l4 and 15 (Fig. 4) adapted to be pressed toward each other so as to enclose the beaded edge 2' of the stringer 2 (Fig. 6) between them, thereby retaining the unit on the stringer. The units illustrated also comprise the upstanding lugs or pins I6, having surfaces I1 substantially perpendicular to the upper surface 9 of the unit, and having cavities l8 in their under surface coaxial with the lugs l6.

" By proceeding in accordance withthe method above indicated, the free outer ends l2 of the units are, as above described, smoothly rounded and finished without recourse to a second operation subsequent to the cutting or dieing operation, and thus may be attached to the stringers directly after they are formed, in accordance with the usual methods and by the usual apparatus. in external appearance, quite similar to those illustrated in my Patent No. 1,658,392, they are superior to the latter by reason of the fact that material) 'to a grinding or tumbling operation.

wholly within the confines of the strip of material. Thus all of the edges of the unit are cut edges such as result from the operation of cooperating dies, and all of thehard dense edge portions of the wire are rejected. These cut edges are sometimes ouite rough and, in fact.

While these units as thus produced, are,

aosavoa may have burrs or substantial projections if the dies are not kept very sharp, and it will be noted that the outer or free end 22 of the unit is substantially vertical and has square corners at its upper and lower ends, such as tend to cause a harsh operation of the slider, with diificult entrance of the units of one series between those of the other, and some danger of scratching the It will also be noted that in cutting units by the method indicated in Fig. 8, a substantial portion of material is left at each side of the strip, whereas in accordance with the new method, indicated in Fig. 3 (where the units are cut from one edge of the strip) much less waste material results. In fact, I find that a saving of as much as 17% or more of the material may be effected by my improved method.

While I prefer to use a drawn or rolled wire as the raw material, since I thereby obtain a fastener unit of improved character capable of withstanding wear as above described, I contemplate the permissive use of. strips or ribbons of sheet material cut to proper width, and the practice of such part only of my method as consists in cutting the units from one edge of the strip. While this latter procedure may be desirable as saving material, it would not produce round edges unless the edge of the strip were first subjected to a rounding and finishing operation, (a step which I contemplate as within the purview of the invention), but more important, it

does not produce a unit having an edge which is hard, dense, and wear-resistant. However, thismethod of cutting units from one edge of a strip, whether such strip be of drawn or rolled wire or merely a ribbon of sheetmaterial, is advantageous as above noted, andJsregarded as falling within the scope of my invention as expressed in the appended claims.

I claim:

1. That method of making fastener units of the class described, which comprises as steps providing an elongate strip of material having substantially parallel edges and whose upper and lower surfaces are substantially parallel and flat from edge to edge, moving said flat strip endwise past appropriate cutting and forming means and by such means cutting and forming individual units one after another successively, each unit as cut having spaced legs, the cutting operation being I so performed that the outer end surface of each unit comprises a substantially unaltered portion of one edge of the strip of material while leaving the opposite edge of the strip intact.

2. That method of making fastener units of the class described, which comprises as steps providing an elongate strip of material having'substantially flat and parallel upper and lower surfaces and a curved edge which merges smoothly into said upper and lower surfaces respectively, and cutting independent fastener unit blanks each, as cut, having spaced legs, from the strip, the cutting operation beingso'performed that the outer end surface of each blank comprises a substantially unaltered portion of the curved edge of the strip of material while leaving the opposite margin of the strip of materialintact.

3. That method of making fastener units of the class described, which comprises as steps pro-.- paring a length of material having a longitudinal edge which is dense, hard andwear resistant, and so cutting a fastener unit blank fromsaid material that theouter end ofsaid blank comprises a substantially unchanged portion of said wearresistant longitudinal edge of the material.

4. That method of making fastener units of the class described, which comprises preparing a length of substantially fiat wire whose outer surfaces are hard, dense and wear resistant and in which the fibers of the material extend longitudinally of the wire, said wire having a rounded edge, and so cutting a fastener unit from the wire that the outer end of the unit comprises a part of the rounded edge of the wire substantially unchanged from its original shape.

5. That method of making fastener units of the class described, which comprises as steps preparing a fiat strip of material having substantially parallel upper and lower surfaces and a cylindrically curved edge which is dense, hard and wear resistant and which merges smoothly into said upper and lower surfaces respectively, and so cutting a unit from said material that the outer end of the unit comprises a portion of the cylindrically curved edge of the material.

G. E. PRENTICE. 

